1. Field of the Invention
The present invention relates to a webbing take-up device that structures a seatbelt apparatus of a vehicle.
2. Related Art
An acceleration sensor is provided at a webbing take-up device that structures a seatbelt apparatus of a vehicle. When the vehicle decelerates sharply, the acceleration sensor operates a lock mechanism in order to restrict rotation of a spool in a pull-out direction. This kind of acceleration sensor has a structure in which an inertial body moves by inertia when the vehicle sharply decelerates, and the lock mechanism is operated by the inertial movement of the inertial body.
A webbing take-up device disclosed in Japanese Patent Application Laid-Open (JP-A) No. 2009-274613 (patent document 1) is incorporated in a seatback of a seat that has a reclining mechanism. Consequently, the attitude of the webbing take-up device tilts in accordance with inclination of the seatback. In the webbing take-up device disclosed in the patent document 1, a sensor case that supports the inertial body of the acceleration sensor is configured so as to be kept horizontal by its own weight irrespective of the attitude (tilt) of the webbing take-up device.
The acceleration sensor of the webbing take-up device disclosed in the patent document 1 is provided with a weight portion at the lower side in order to lower the center of gravity of the inertial body. As a result, the inertial body, and hence the acceleration sensor, is increased in size.